So the asynchronous nature of Aeshna umbrosa is natural while the other four are all synchronous by nature. Are there major differences in environmental niche the 4 inhabit vis-a-vis Aeshna umbrosa? Seems it would have to be if the photoperiod is the determinant.
What is the timeline in the natural habitat for each species? Do they develop at different times during the season? Timed with predation?
What of the possibility that Aeshna umbrosa was late to the evolutionary party and this asynchronous timing was advantageous due to competition?
I'm just spouting.
I'm not a bug guy. I have no idea what I'm talking about. But this is interesting.
The bug guys I knew in school were quite adept at improvising equipment because of their penchant to chase creepy-crawlies into dark corners on the spur of the moment. But your professional stuff and the professional results you get from it? Ouch!